Infinite platen variable



July 1, 1958 s. B. TIBBLING INFINITE PLATEN VARIABLE Filed Feb. 20. 1956 INVENTOR. STIG 8. TI BBLING @aflt ATTORNEY reg "any

2,8412%! Fatented July 1, 1958 nsrmrrs rLArnN VLE Stig it. Tibbling, Hyde Park, N. Y., assignor to International Business Machines Corp-oration, New Yarn, N. Y., a corporation of New York Application February 2%, E56, Seriai No. 566,591

6 Claims. ((13. 197-423) This invention relates to improvements in variable line spacing clutches commonly used in connection with the platens of typewriters, adding machines, accounting machines, and other oflice machines.

The principal object of the invention is to provide an improved clutch which permits adjustment of clutched members relative to each other any desired amount.

Another object is to provide a variable spacing clutch which is cheaper to manufacture and assemble.

A further object is to provide a variable spacing clutch which may be quickly assembled or disassembled for cleaning, repair, and lubrication.

Still another object is to provide a clutch band operating mechanism which is unique in its simplicity of structure and is inexpensive to manufacture.

A still further object is to provide a variable spacing clutch that does not require a special platen core or a straight-through platen shaft.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings which disclose, by way of example, the principle of the invention and the best mode which has been contemplated of applying that principle.

In the drawings:

Fig. l is a longitudinal section of one end of a platen with the improved clutch attached.

'Fig. 2 is an exploded diagrammatic view showing the relationship of the parts in the improved clutch.

Fig. 3 discloses two operable positions of a split ring used in the clutch.

Referring to the drawing, and more particularly to Fig. 1, there is shown an improved clutch 1 for connecting a platen 2 of a typewriter in driven relation with a ratchet wheel 3 which may either by rotated by any suitable means not shown, or act as a detent member on manual rotation of the platen. The platen comprises, as

shown herein, a metallic tube 5 supporting a shell 6 which may be of rubber or other suitable resilient material in accordance with the usual practice in the art. Forced into one end of the tube 5 is a platen supporting hub 8 which may be a die-casting of some light metallic alloy such as Duralumin or may be turned from bar stock as desired.

Secured to the hub 8 by means of a pair of screws 9, as shown in Fig. 2, is a cap member iii. Extending axially through the cap member is an opening 12, and surrounding this opening at the right hand side of the cap is a flange 14- adapted to fit into a recess 15 in the hub 8 for aligning the parts. Connected to the cap around the opening 12 at its left hand end is a tubular member 16, and fixed to the tubular member is a sleeve 17 adapted to cooperate with a platen support, not shown, for holding the platen against longitudinal movement. Mounted upon the sleeve 17 is a knob 18 which may be operated manually for rotating the platen to any desired position. Slidably mounted within a central opening in the knob is a button 24 having a reduced portion 21 extending into the left hand end of the tubular member 16.

Formed in the side of the cap Iii adjacent the hub 8 is a slot 22 extending diametrically of the cap and opening at its ends through a reduced cap portion 23 of cylindrical shape. Rotatably received within the slot 22 is a pivot member 24 having a rectangular cam element 25 fixed to one end and resting upon the surface of the cap portion 23. Surrounding the cap portion 23 is a split ring 25 having its ends normally engaging the sides of the cam element 25. The ratchet wheel 3 surrounds the split ring with only a slight clearance between them and is held in place adjacent the hub 8 by an enlarged portion 28 on the cap it). The pivot member 24 has rectangular portions 36 spaced equal distances from its mid-point, and each of these portions fits into a rectangular opening in a side of elongated lever 31 which is U-shaped in cross section. Formed in the supporting hub 8 is an elongated slot 32 through which the lever extends into the interior of the tubular member 5. Fixed to the cap it) is a bracket 33 which also extends through the slot 32 into the member 5 to substantially the same extent as the lever 31 and in parallel relation with the latter. Mounted upon the right hand end of the bracket is a pulley 35. A ball chain 36 is connected to the free end of the lever 31, extends over the pulley 35 and a spoolshaped guide portion 37 of the pivot member 24, then passes through the tubular member 15 and is connected to the reduced portion of the button 20.

Arranged within the tubular member 16 is a spring 38 which acts between the button and a shoulder 39 on the member 16 to apply a tension of the chain. The tension is such as to rock the lever 31 and turn the pivot member 2% clockwise, as viewed in Fig. 2, so that the cam element 25 acts on the ends of the split ring 26 and expands the latter to engage the inner surface of the sprocket wheel. The platen is then directly connected to the sprocket wheel through the split ring, the pivot member 24, the cap 10 and the supporting hub 8. When it is desired to change the position of the platen relative to the sprocket wheel, it is only necessary to press the button 20 so that it moves against the action of the spring 38. This removes the tension on the chain 36 and permits the split ring to contract until it is free of the sprocket wheel. The knob 18 may then be rotated manually to turn the platen free of the sprocket wheel.

It will be appreciated that the movements of the button 2i) and the free end of the lever 31 are large in contrast to the movement of the cam element 25 and the end of the split ring 26. This makes it unnecessary that many or" the parts be fitted accurately, and the greater tolerances permitted result in a less expensive structure.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. In a business machine having a-rotatable platen and a ratchet wheel operable for rotating said platen, a clutch mechanism for controlling a driving connection between said platen and said ratchet wheel comprising, in corn bination, a member fixed to said platen and having a cylindrical portion extending through said ratchet wheel, a split ring clutching eiement mounted concentrically between said ratchet wheel and said cylindrical portion, said split ring clutching element being normally free of said ratchet wheel but adapted to be expanded into clutching engagement with the latter, a pivot element supported by said member and having a cam portion engaging the ends mechanism for controlling .a'driving connection between said platen and said ratchet wheel comprising, in cornbination, a member fiXed to said platen and having a cylindrical portion extending throughsaid ratchet wheel, a

split ring clutching element mounted between said ratchet wheel and said cylindricalportion, a pivot element supported'by said member and having a cam portion engagmg the ends of said split ring elutching element,- a knob fixed tosaid member for rotating said platen, a button slidably received Within an opening insaid knob, means connecting said button to said pivotelement, and a spring acting on said button for rotatingsaid pivot element to effect an expansion of said split ring clutching element into driving engagement'withsaid ratchet wheel, said button operating when pressed: inwardly to compress said spring and permit said split ring'clutching element todi'sengage said ratchet wheel so that said platen may be rotated'by said knob free of saidratchet wheel.

3. In a business machine having arotatable platen and a ratchet wheel operable for rotating saidplatema clutch mechanism for controlling a driving connection between said platen and said ratchetwheel comprising'in combination, a member fixed to said platen and having a cylin-.

drical portion extending through said ratchet wheel, a split ring clutching element mountcd between said ratehet wheel and said cylindrical portion, a pivo-t element supported by said member and having 362111 portion engaging the endsof said split ring clutching element, a knob fixed to said member for rotating said platen, a button slidably, received within an opening in said knob, means connecting said button to said p ivot element, said means comprising a lever fixed to said pivot-element and extending within said platen and a flexible element connected atits ends to said button and said lever, and a spring acting onr said button for rotating said piv ot element tofitfectjan ex pansion of said split ring clutching element into driving engagement with said ratchet wheel, said buttonoperating when pressed inwardly to compress said spring and permit said split ring clutching element to disengage said ratchet wheel so that said platen may be rotated by said knob free of said ratchet wheel. 7 v a 4. In a business machine having a rotatableplatenland a ratchet wheel operable for rotating said platen, a clutch mechanism for controlling a' driving connection between said platen and saidratchet wheel comprising, in combination, a member fixed to said platen and having a cylin- 7 said members whereby a releasable drive is provided be-' drical portion extending through said ratchet wheel, a split ring clutching element mounted between said ratchet wheel and said cylindrical portion, a pivot element sup ported by said member and having a cam portion engaging the ends of said split ring clutching element, a knob fixed to said member for rotating said platen, a button slidably received withina'n opening in said knob, a lever fixed to said pivot'element, a flexible strand connecting; said knob and said lever, and a spring acting through said button, said strand, a'ndisaid lever, for rotating said pivot element to'eifect an expansion of said split'ring clutching element into driving engagement with said ratchet wheel, said button operating when p'ressed inwardly to compress said spring relieving tension on said strand, said lever and said pivot elementand permitting said split ring clutching element to disengage said ratchet wheel so that said platen may be rotated by said knob free ofsaid ratchet Wheel.

5. In a business machinehaving a rotatable platen and a ratchet wheel operable for rotating "said platen, a clutch mechanism for controlling a driving connection between said platen and said ratchet wheel comprising, in combination, a cap fixedto one end of said platen and having a cylindrical portion extending through said ratchet wheel,- a tubular memberfixed to said cap, a knob attached to said tubular member for rotating said platen, said knob" having an opening communicating Withsaid tubular'memher, a split ring clutching element arranged between said ratchet wheel and the cylindrical portion of said cap, a

pivot member supported by said cap and having a cam portion extending between the ends of said split ring clutching element, a'button slidably received Within the opening in saidknob, means connecting said button to said pivot member, anda spring received within said tubu-tlar member and acting'on saidbutton for effecting an expansion of said split ring clutching element into driving engagement with said ratchetwheel. V

6. In a business machine having a rotatable platen and a ratchet wheel operable for rotating said platen, a clutch mechanism for controlling .a driving connection between said platen and said ratchetmember.comprisingin coinbination, a cylindrical member fixed'to said platen and extending through said ratchet memberfa splitring clutch-:

ing element mounted concentrically betweenisaidratchet member and said cylindrical member and in direct driving relation with oneof said members, and means controlling the diameter of said split ring clutching element for placing it in releasable driving relationship with the;other of tween saidrat'chetand said platen.- 7

References Cited in the file t this patent 5v UNITED STATES PATENTS 1,792,105 7 Luce Feb/10,1931

1,889,047 Friedmann Nov.:29, 1932 

